The invention relates generally to power-driven conveyors and, more particularly, to methods and devices for making measurements of conditions local to modular conveyor belts from within the belts and wirelessly transmitting those measurements for monitoring or controlling the operation of the belt or the process in which it is used.
U.S. Pat. No. 4,587,852, “Conveyor Belt Tension Sensing,” describes a radio transmitter and a tensile force sensor that includes strain gauges mounted in the limbs of a support link that is adapted for connection to joint components at the ends of straight-running flat belt portions. The strain gauges sense belt tension and derive a corresponding signal that is transmitted by the transmitter to a receiver and monitor. The belt has to be unlaced and relaced every time the support link is installed or removed. And because the belt is longer with the support link installed, the tension has to be adjusted.
It is often desirable to detect the tension at the outside of a modular plastic conveyor belt in a spiral conveyor. Knowing the tension in a side-flexing spiral or radius belt at the outside of a turn is useful in detecting imminent failures or in adjusting the tension for optimal operation. This is conventionally done in spiral belt conveyor systems by a data-logging tension-sensing device temporarily attached along outer belt modules as the belt follows its helical path along the spiral conveyor's drive tower. But the sensing device has to be removed before it reaches the belt's return path and falls off. When the device is removed, the belt tension data it collected is dumped to a computer for analysis.
Thus, there is a need for a device that can sense conditions, such as belt tension at the outside of a turn, in a conveyor belt without being destroyed and without having to be removed from the belt.